1. Field of the Invention
This invention relates to a control system for a burner and one object of the invention is to provide means for automatically controlling operation of the burner so that the excess air as actually measured is maintained close to a desired value.
2. Description of the Prior Art
It is usual to operate boilers by controlling the fuel supply and the air supply independently in stoichiometric proportions, although it is necessary to have some excess air to ensure that combustion is complete even if the air and fuel are not perfectly mixed. Excess air however requires to be heated without producing any useful effect, and therefore represents a loss of efficiency, and the smallest amount of excess air that can be used while ensuring that there is complete combustion, the more efficient will the boiler be. The expression `boiler` includes such similar pieces of apparatus as hot air or gas generators and ovens.